Method of forming tobacco composition



Patented Sept. 19, 1961 3,000,383 METHOD OF FORMING TOBACCO COMPOSITION James A. de Tomasi, Cold Spring Harbor, N.Y., assignor to American Machine & Foundry Company, a corporation of New Jersey No Drawing. Filed Sept. 1, 1955, Ser. No. 532,117 1 Claim. (Cl. 131140) This invention relates to an aqueous tobacco dispersion characterized by a substantially stable viscosity at a pH lower than 3.5. More particularly, the invention relates to a dispersion of tobacco particles in a polysaccharide acidic water medium and to methods of forming such compositions.

In the manufacture of tobacco sheet material from finely divided tobacco, tobacco particles are commonly dispersed in water together with a polysaccharide adhesive material. The slurry is then processed into sheets and dried.

Heretofore, such slurries have often been characterized by short storage life because of sudden losses in viscosity. Ordinarily, adhesive polysaccharides give desirable plastic thickening qualities to the tobacco dispersion and aid physically in such sheet forming operations as extrusion and calendering.

Undersirable viscosity losses seem to be related to the association of tobacco particles with aqueous polysaccharide compositions, since these compositions exhibit substantially stable viscosities before contact with some kinds of tobacco. Different kinds of tobacco appear to affect the viscosity of these preparations in different degrees but insofar as there is an observable effect, preparations tend to become less viscous.

Therefore, it is an object of this invention to provide an aqueous polysaccharide tobacco composition of substantially stable viscosity.

It is also an object of this invention to provide a method of forming an aqueous polysaccharide tobacco composition of substantiaHy stable viscosity.

These and other objects of the invention are elaborated and become more apparent in the following description.

Aqueous tobacco dispersions which do not lose viscosity upon standing can be prepared in several ways. According to one method tobacco particles are added to water and the dispersion is acidified. A polysaccharide thickening agent is then mixed into the tobacco dispersion. It has been suggested that when tobacco is left in an aqueous dispersion of very low viscosity valuable soluble tobacco flavors are leached from the tobacco. Consequently, by another method of this invention a viscous aqueous polysaccharide composition is first prepared. Finely divided tobacco is added to this and immediately acidified.

Various polysaccharides can be used to form viscous tobacco dispersions for the manufacture of tobacco sheet material. Among these are cellulose derivatives, .pectins and pectinates, algins and alginates and sundry plant gums such as galactomannans. All of these adhesives can be treated with water and tobacco according to this invention.

It is postulated that the degradation of polysaccharide units promoted by catalytic material found in tobacco is inhibited by an acid environment. Most degradation is controlled by adjusting the acidity to about pH3 but slightly lower pH levels are sometimes necessary for satisfactory control of viscosity and these may be as low as about pH 2.

Different acids can be used to adjust the acidity of tobacco slurries but mineral acids are satisfactory for most purposes. It is important that combustion products of the finished tobacco sheet are not adversely affected by the acid addition. Volatile acids are preferred since these are largely expelled when the tobacco sheetis dried. Hydrochloric and nitric acids are satisfactory and nitric acid is preferred where salty flavor in the tobacco sheet is a problem.

A dispersion of finely divided tobacco in water is a highly buttered system and a considerable amount'of acid is consumed in adjusting the pH of such a system to a value of 3 or lower. Moreover, catalytic inactivation reactions at temperatures which do not harm the tobacco are generally slow and may require as much as thirty minutes to an hour to reach a stable condition at 40 C.

When an aqueous polysaccharide tobacco dispersion, not acidified according to this invention, is allowed to stand, the viscosity, measured on a Brookfield viscometer, may drop in one quarter of an hour or less from- 800 centipoises to as low as 20 centipoises.

However, when the same dispersion is treated according to this invention, the viscosity will not decrease appreciably upon standing for as long as five hours or more and may, indeed, show as much as a five fold increase to a value such as 5,000 centipoises. This result is not only totally unexpected but has an innate economic value in that valuable adhesive can be replaced by inexpensive acid.

Still another advantage of this invention is realized when sodium carboxymethyl cellulose is selected as a polysaccharide adhesive. This soluble salt forms a water insoluble dispersion in the critical pH range between 2 and 3 where the viscosity is stabilized. Consequently, this invention is well adapted to the manufacture of water insoluble tobacco sheets. Sodium carboxymethyl cellulose is usually less sensitive to degradation catalysis by tobacco materials then is cellulose glycolic acid. However, an acid environment controls degradation of cellulose glycolic acid.

The invention is further illustrated by the following examples which show in detail ways of preparing tobacco compositions of this invention.

Example one According to a preferred example of a method of forming a tobacco composition of stable viscosity according to this invention one part of dry sodium carboxymethyl cellulose powder was mixed with seventy two parts of water to form a solution. To this solution nine parts of tobacco were added and the pH was maintained just below 3 by the addition of hydrochloric acid. The viscosity of the tobacco dispersion did not decrease during the next six hours. A sample of the dispersion which was not acidified below pH 3.5 dropped in viscosity more than ninety five percent in fifteen minutes.

Example two One part of dry sodium carboxymethyl cellulose was dispersed in seventy two parts of water and the dispersion was acidified to about pH 2.7. Nine parts of dry tobacco were added to the acid dispersion which had converted to cellulose glycolic acid and the pH was maintained at about 3 by additional acid. The buffering action of the tobacco tended to increase the pH. tobacco slurry did not decrease in viscosity for more than ten hours.

Example three Nine parts of finely divided tobacco which passed a sixty mesh screen were mixed with seventy two parts of water and the pH of the dispersion was adjusted to a value of 3 which was maintained by adding additional acid over a period of thirty minutes at 40 C., as the system came into equilibrium. One part of dry sodium carboxymethyl cellulose was added to this dispersion and the initial viscosity did not decrease over a period of at least five hours.

There: have thusbeen described aqueous tobacco dispersions containing polysaccharide thickening agents which do not decrease in viscosity when stored for several hours. 'Iherehave-also-been described-methods-of forming-these tobacco compositions.

What isclaimed is:

A method of making a viscous tobacco slurry which comprises combining finely divided dry ground tobacco and-sodium carboxymethyl cellulose in water to form a composition, acidifying said composition and maintaining the acidity of said composition at a pH between 2 and 3, whereby sodium carboxymethyl cellulose is insolubilized as cellulose glycolic acid and the viscous character of saidcomposition is preserved.

References- Cited in the tile of this patent UNITED STATES PATENTS 10 OTHER REFERENCES Encyclopedia of Chemical Technology, volume 3,

Published 1949 by Interscience En- 387, lines 8-26. cyclopedia Inc. New York, N.Y. 

